Re: 1957 Johnson 10hp and 18hp gears Home › Forum › Ask A Member › 1957 Johnson 10hp and 18hp gears › Re: 1957 Johnson 10hp and 18hp gears XR55US Member - 2 YearsReplies: 310Topics: 30 July 3, 2018 at 2:35 am #78931 The numbers for a 1957 10hp are from a Johnson paper parts list for 1957 motor. A 1957 Johnson 18hp paper parts list only shows the gear set number.